Sweeping elements

ABSTRACT

A fire resistant sweeping element comprising a filamentary mixture of polyvinyl chloride filaments and polypropylene filaments, the polyvinyl chloride filaments being included in an amount sufficient to restrain combustion of the polypropylene filaments.

United States Patent 11 1 Shaw et al. Aug. 20, 1974 [54] SWEEPING ELEMENTS 2,100,138 11/1937 Heldt ,2 15/159 A 3,207,556 9/1965 Lechene 15/159 A [75] Inventors: Shaw, Mlddlebury 3,357,038 12/1967 Williamson 6161 lS/l83 1 Thompson, Bflsml, both of 3,668,732 6/1972 Lardel'lOiS 15/159 A [73] Assignee: Polymers Inc., Mitldlebury, Vt. Primary Examiner peter Feldman 22 Filed; 2 1973 Attorney, Agent, or FirmLarson, Taylor & Hinds [21] Appl. No.: 329,123

[57] ABSTRACT [52] US. Cl. 15/159 A, 15/106 [51] Int. Cl A46b 9/06 A fire resistant sweepmg element Comprising a [58] Field 61 Search 15/159 R, 159 A, 106, 229, mentary mixture of P y y chloride filaments and 15/167, 182, 187, 181, 179, 180, 183 polypropylene filaments, the polyvinyl chloride filaments being included in an amount sufficient to re- [56] References Cited strain combustion of the polypropylene filaments.

UNITED STATES PATENTS 2,043,758 6 1936 Lay 15/159 R 2 Clams 2 Drawmg F'gures PATENIEllnuczo I974 J/ ////K//// //////J// SWEEPING ELEMENTS This invention relates to sweeping elements for incorporation in brooms or the like.

The sweeping elements of such brooms have previously consisted of filaments of natural vegetable corn fibre. Due, however, to the unsteady supply and constantly rising price of such vegetable corn fibre, alternative substitutes have been sought for incorporation in brooms.

It has previously been proposed to use synthetic filaments of polypropylene as a substitute in view of its very lightweight, ready availability, ease of fabrication and increasingly competitive price. Unfortunately polypropylene has the disadvantage that it is very prone to cold flow or permanent distortion when subjected to external forces so that it is difficult to maintain the shape of a polypropylene filament broom during normal usage. An additional disadvantage is that since polypropylene consists completely of hydrocarbon it is readily flammable and constitutes a fire hazard in its usual form. Drippings from a polypropylene broom during combustion adds greatly to the spread and continuation of a fire.

An object of the present invention is to provide a sweeping element for a broom or the like in which the aforesaid disadvantages are obviated or mitigated.

According to the present invention, there is provided a filamentary sweeping element comprising a mixture of at least 20 percent by bulk of polyvinyl chloride filaments, the remainder being predominantly filaments of polypropylene.

BRIEF DESCRIPTION OF DRAWINGS DESCRIPTION OF TEST EMBODIMENT Arranged filaments I of a sweeping element under test are retained by a metallic band 2 by means of rivets 3, 3a, 3b and 30; said metallic band having affixed to it a metallic loop 4 to which is further attached a metallic rod 5. The upper end of rod 5 is free to move into and through tubular section 6. To one side of tubular section 6 there is an extension 7 through which a hole 8 has been formed and through which rod 9 passes in such manner that tubular section 6 with extension 7 may turn freely on rod 9. Rod 9 is made in U form and its two ends are fastened to metal pads 10 and 11 which are nailed or otherwise fixed to wall 12.

Since rod 5 slides freely at all times through tubular section 6, the filaments l are resting on the floor 13 at all times. Initially the test brooms were rested at a 12 angle with reference to wall 12. The test broom filaments curved gradually during each test under the weight of the filament, holding band 2, loop 4, and rod 5, as shown in FIG: 2 by the broom illustrated by dotted lines. As the filament curved, rod 5 assumed a lesser angle with respect to wall 12 than the 12 initially assumed. Brooms of this type may be stitched as at 15 for appearance and for sweeping action consideration. The weight of the filament retaining metal band 2, rivets 3 3c, loop 4, and rod 5 was one pound or the weight equivalent to a normal wooden broom handle plus customary means of attaching the broom filaments to said handle. Cold flow or distortion was measured by the maximum distance D the fibres deviated from the line of rod 5 and was measured at right angles from the front face of metallic band 2 as shown in FIG. 2.

Using the apparatus illustrated, tests were carried out to compare the cold flow and flammability characteristics of a sweeping element consisting wholly of polypropylene filaments with sweeping elements incorporating polypropylene filaments and varying percentages by bulk of polyvinyl chloride filaments.

The filaments utilized in the tests were of the finned type described in US. Pat. No. 2,637,893, the crosssection of the filaments being X-shaped and the dimension between opposing chords of the X being in the order of 0.040 inch to 0.050 inch. Such brooms may contain 10 ounces of polypropylene filament 12 inches long. Any part of the polypropylene replaced by polyvinyl chloride would be heavier in the ratio of 1.40 to 0.92, the specific gravities of polyvinyl chloride and polypropylene respectively. For example were polypropylene to be replaced by polyvinyl chloride completely the equivalent weight for polyvinyl chloride would be 10 X 1.40/0.92 15.2 02. It follows that it is desirable to maintain as much polypropylene in the broom as possible to keep the broom light in weight.

The following illustrates the cold flow characteristics of polypropylene filaments and that of polypropylenepolyvinyl chloride filament mixtures:

During free recovery the filaments were suspended off the floor.

Thus, while polypropylene filament still remains the largest bulk component in the filament mixture, it was found by the tests that the inclusion of at least 20 percent preferably 25 percent to 40 percent of polyvinyl chloride filament very effectively lowers the amount of permanent cold flow or distortion experienced by the sweeping end of the broom.

Additionally, there is great concern today over the flammability of consumer products. Flammability tests were made on the brooms 'cold flow tested and reported in Table I. The test consisted of lighting wood chips on a steel plate and sweeping the hot coals around until the characteristics of each broom were determined. I

The results were:

TABLE 2 Bulk Percent Polypropylene Filament Effect of Wood Fire Broom filler filament burns rapidly with flame. Broom destroyed. Melted polypropylene streams from broom forming puddle on steel plate. Puddle burned long after wood fire had died down.

Broom filler filament catches fire with some difficulty. Significant drippings of polypropylene on steel plate.

Broom catches fire lcss readily than broom containing l percent polyvinyl chloride. Significant drippings of polypropylene on steel plate and which continued to burn for some considerable period. Small, isolated individual filament flame flares quickly smothered by adjacent polyvinyl chloride filaments and readily extinguishable. Charring and shrivelling of external filaments but shape of broom maintained. Some evidence of limited drippingv Broom very difficult to start flaming. Flames self-extinguished within 2 minutes and the burning rate was extremely slow. Shrinkage very evident. No dripping.

Same charring and shrivelling of outside filaments. Shape of broom retained. N0 flame or dripping.

The admixture of a suitable percentage of filaments of polyvinyl chloride results, during excessive heating, in the production of a non-flammable blanket of hydrogen chloride which satisfactorily reduces the flammability of the mixture.

Thus, a mixture of filaments for brooms containing 20 to 40 percent by bulk polyvinyl chloride filaments and 60 to percent polypropylene filaments accomplishes the dual function of overcoming the weaknesses of polypropylene alone, namely, excessive cold flow and flammability, even though polypropylene remains the dominant filament by bulk in the mixture.

By the term sweeping element as used in the specification and claims, it is to be understood that the form of the sweeping element need not necessarily be of the form illustrated in FIGS. 1 and 2. The invention is equally applicable to other forms of sweeping elements for incorporation in manually or mechanically operated brooms or brushes.

The term bulk as used in the specification and claims in relation to a sweeping element is intended to mean the total cross-sectional area of the filaments which make up said sweeping element.

What is claimed is:

1. A filamentary sweeping element comprising a mixture of at least 20 percent by bulk of polyvinyl chloride filaments, the remainder being predominantly filaments of polypropylene.

2. A sweeping element as claimed in claim 1, in which the filaments of polyvinyl chloride are of an amount from 25 to 40 percent by bulk. 

2. A sweeping element as claimed in claim 1, in which the filaments of polyvinyl chloride are of an amount from 25 to 40 percent by bulk. 